Companion animal treatments

ABSTRACT

The invention relates to minimizing the progression of cancer in a companion animal using P2X7 immunotherapy.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a US national stage of PCT/AU2011/001166, filed Sep. 9, 2011, which is incorporated in its entirety, and which claims the benefit of AU2010904080, filed Sep. 10, 2010, and AU2011902626, filed Jul. 1, 2011.

INCORPORATION BY REFERENCE OF SEQUENCE LISTING

The sequence listing written in file 430898SEQLIST3.TXT is of 95 kilobytes and was created Jan. 18, 2015. The information contained in this filed is hereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to veterinary oncology, including treatment of cancer in companion animals.

BACKGROUND OF THE INVENTION

Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.

The incidence of cancer in companion animals, such as dogs and cats and the like is increasing, and cancer is now considered to be the leading cause of death in older animals. It is believed that the annual incidence rate for cancers in dogs is about 2 to 2.5% (about the same as humans) and about 1.5 to 2% for cats.

The cancers having the highest incidence in dogs are in the following order: lymphoma (about 20%); mast cell tumor (about 18%); soft tissue sarcoma (about 10%); hemangiosarcoma (about 10%); osteosarcoma (about 9%). The remaining segments typically include squamous cell carcinoma, mammary carcinoma, melanoma, histiocytoma and fibrosarcoma.

The cancers having the highest incidence in cats are in the following order: lymphoma (about 25%); mast cell tumor (about 22%—of cutaneous neoplasms); squamous cell carcinoma (>11% of cutaneous neoplasms); mammary carcinoma (about 10%); and the remaining segments include hemangiosarcoma, osteosarcoma, fibrosarcoma, sebaceous hyperplasia/adenoma.

Approaches to cancer treatment in veterinary oncology include surgery, radiation therapy, hyperthermia therapy, photodynamic therapy and chemotherapy. Gene therapy and immunotherapy have not been widely implemented.

Apart from Palladia (toceranib phosphate; Pfizer), no medicines have been given marketing approval for use as chemotherapeutics for cancer treatment in companion animals. This is mainly because of the high costs associated with obtaining marketing approval.

In most jurisdictions, veterinary oncologists have “off-label” drug use privileges. Off-label drug use means that the veterinary oncologist can use drugs approved for one species (including humans) freely in another species. With these privileges, a common practice has arisen in veterinary oncology whereby the oncologist tends to select those chemotherapeutics for use in cancer treatment of companion animals for which significant clinical experience has been obtained in human oncology.

Examples of chemotherapeutics and relevant indications currently used in veterinary oncology are shown in Table 1.

TABLE 1 Chemotherapeutic Type of cancer Alkylating agents Cyclophosphamide (Cytoxan) Lymphoma, mast cell tumors, mammary tumors, hemangiosarcomas Ifosfamide (Ifex) Chemoresistant lymphoma, soft tissue sarcoma Chlorambucil (Leukeran) Leukemias, mast cell tumors, lymphoma Melphalan (Alkeran) Multiple myeloma Busulfan (Myeleran) Leukemias Procarbazine Hyd (Matulane) Lymphoma Plant alkaloids Vincristine (Oncovin) Lymphoma, venereal tumors, mast cell tumors, sarcomas Vinblastine Lymphoma, mast cell tumors Antimetabolites Methotrexate Lymphoma, osteosarcoma Cytosine arabinoside CNS lymphoma, leukemia (Cytostar, Ara-C) Fluorophyrimidines Skin tumors, mammary carcinoma, (Fluorouracil [5-FU]) GI tumors Hydroxyurea Recurrent leukemias Antitumor antibiotics Doxorubicin Lymphoma, hemolymphatic (hydroxydaunomycin) malignancies, carcinomas and saracomas including osteosarcoma Epirubicin (Pharmorubicin) Lymphoma Methoxymorpholinodoxorubicon Chemoresistant lymphoma, sarcomas and carcinomas Mitoxanthrone Oral squamous cell carcinoma, lymphoma, sarcomas and carcinomas Bleomycin Squamous cell carcinoma Actinomycin D Lymphoma, sarcoma, carcinoma Platinum compounds Cisplatin (Platinol) Osteosarcoma, skin and nasal carcinomas Carboplatin (Paraplatin) Skin and nasal carcinomas Lobaplatin Osteosarcoma Nitrosoureas Lomustine Brain and CNS tumors, lymphomas, mast cell tumors Carmustine Brain tumors Topoisomerase I inhibitors Camptothecins Lymphoma Hormones Prednisone Lymphomas and mast cell tumors Biologic Response Modifiers Peroxicam (Feldene) Squamous cell carcinoma, mammary adenocarcinoma, transmissible venereal tumors Muramyl dipeptide Splenic hemangiosarcoma, osteosarcoma Retinoids Etretinate (Tegison) Cutaneous lymphoma, mycosis Isotretinoin (Accutane) fungoides Other Paclitaxel (Taxol) Mammary carcinomas, lymphomas Darcarbazine Recurrent lymphoma, melanoma, sarcomas L-asparaginase (Elspar) Lymphoid malignancies, mast cell tumors

There are a number of problems and limitations concerning these chemotherapies. For example, as observed in human therapy, these compounds are associated with toxicities linked with the non specific action against dividing cells including bone marrow, gastrointestinal epithelia and hair follicles. Side effects include immunosuppression, anaemia, nausea and vomiting, delayed wound healing, reproductive failure and hair loss. Some specific organs may also be susceptible including heart, kidneys and CNS.

Also, the use of a single chemotherapeutic agent is rarely effective for curing cancer, as not all tumor cells will be effectively killed by a single agent. One reason for this is that as cancer cells develop, so too does the incidence of mutation that may result in resistance phenotypes. Therefore, in most situations it is necessary to develop a combination chemotherapy for the given clinical case.

There is a need for an alternative or improved treatment of cancers of companion animals, and especially those cancers having a higher incidence in companion animals.

There is also a need for an alternative or improved treatment of cancers in dogs.

There is a need for treatment of lymphoma, mast cell tumor, soft tissue sarcoma, hemangiosarcoma, osteosarcoma, squamous cell carcinoma, mammary carcinoma, melanoma, histiocytoma and fibrosarcoma in dogs.

There is also a need for an alternative or improved treatment of cancers in cats.

There is a need for treatment of lymphoma, mast cell tumor, squamous cell carcinoma, mammary carcinoma, hemangiosarcoma, osteosarcoma, fibrosarcoma, and sebaceous hyperplasia/adenoma in cats.

SUMMARY OF THE INVENTION

The invention seeks to address one or more of the above mentioned needs and in a first aspect provides a method for minimising the progression of cancer in a companion animal, the method including the steps of:

-   -   providing a companion animal in which the progression of cancer         is to be minimised; and     -   providing in the animal a whole antibody, or a fragment thereof         including a variable domain for binding to a non functional P2X₇         receptor that is expressed by the animal;

thereby minimising the progression of cancer in the animal.

In a second aspect the invention provides a method for minimising the progression of cancer in a companion animal, the method including the steps of:

-   -   providing a companion animal requiring treatment for cancer; and     -   forming an immune response in the companion animal to a         non-functional P2X₇ receptor;

thereby minimising the progression of cancer in the companion animal.

In a third aspect the invention provides a method for minimising the progression of cancer in a companion animal, the method including the steps of

-   -   providing a companion animal that has received a non self         antigen binding site for treatment of the cancer;     -   forming an immune response in the companion animal to a         non-functional P2X₇ receptor;

thereby minimising the progression of cancer in the companion animal.

In a further aspect of the invention there is provided a use of:

-   -   a whole antibody, or a fragment thereof including a variable         domain for binding to a non functional P2X₇ receptor; or     -   a P2X₇ receptor, or a fragment of a P2X₇ receptor;

in the manufacture of a medicament for treatment of cancer in a companion animal.

In yet a further aspect the invention provides a use of:

-   -   a whole antibody, or a fragment thereof including a variable         domain for binding to a non functional P2X₇ receptor; or     -   a P2X₇ receptor, or a fragment of a P2X₇ receptor;

for treatment of cancer in a companion animal.

In still further aspects the invention provides a kit or composition for use in the treatment of a cancer in a companion animal, the kit including:

-   -   a whole antibody, or a fragment thereof including a variable         domain for binding to a non functional P2X₇ receptor; or     -   a P2X₇ receptor, or a fragment of a P2X₇ receptor;     -   written instructions for use in a method or any one of the         preceding claims.

Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Amino acid sequence of P2X₇ receptor.

FIGS. 2A-K. Alignment of amino acid sequence of canine and human P2X₇ receptors.

FIG. 3. Anti E200 antibody response detected by ELISA.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to certain embodiments of the invention. While the invention will be described in conjunction with the embodiments, it will be understood that the intention is not to limit the invention to those embodiments. On the contrary, the invention is intended to cover all alternatives, modifications, and equivalents, which may be included within the scope of the present invention as defined by the claims.

One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. The present invention is in no way limited to the methods and materials described.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the animal features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

All of the patents and publications referred to herein are incorporated by reference in their entirety.

A Definitions

For purposes of interpreting this specification, the following definitions will generally apply and whenever appropriate, terms used in the singular will also include the plural and vice versa. In the event that any definition set forth conflicts with any document incorporated herein by reference, the definition set forth below shall prevail.

As used herein, except where the context requires otherwise, the term “comprise” and variations of the term, such as “comprising”, “comprises” and “comprised”, are not intended to exclude further additives, components, integers or steps.

“Companion animal” generally refers to an animal that is a pet or “companion” of a person. Cats (Felines) and dogs (Canines) are examples.

“Purinergic receptor” generally refers to a receptor that uses a purine (such as ATP) as a ligand.

“P2X₇ receptor” generally refers to a purinergic receptor formed from three protein subunits or monomers, with at least one of the monomers having an amino acid sequence substantially as shown in FIG. 1, or a canine sequence substantially as shown in FIGS. 2A-K. To the extent that P2X₇ receptor is formed from three monomers, it is a “trimer” or “trimeric”. “P2X₇ receptor” may be a functional or non-functional receptor as described below. “P2X₇ receptor” encompasses naturally occurring variants of P2X₇ receptor, e.g., wherein the P2X₇ monomers are splice variants, allelic variants and isoforms including naturally-occurring truncated or secreted forms of the monomers forming the P2X₇ receptor (e.g., a form consisting of the extracellular domain sequence or truncated form of it), naturally-occurring variant forms (e.g., alternatively spliced forms) and naturally-occurring allelic variants. In certain embodiments of the invention, the native sequence P2X₇ monomeric polypeptides disclosed herein are mature or full-length native sequence polypeptides comprising the full-length amino acids sequence shown in FIG. 1, or a canine sequence substantially as shown in FIGS. 2A-K. In certain embodiments the P2X₇ receptor may have an amino acid sequence that is modified, for example various of the amino acids in the sequence shown in FIG. 1 or a canine sequence substantially as shown in FIGS. 2A-K may be substituted, deleted, or a residue may be inserted.

“Functional P2X₇ receptor” generally refers to a form of the P2X₇ receptor having a binding site or cleft for binding to ATP. When bound to ATP, the receptor forms non-selective sodium/calcium channel that converts to a pore-like structure that enables the ingress of calcium ions into the cytosol, one consequence of which may be programmed cell death. In normal homeostasis, expression of functional P2X₇ receptors is generally limited to cells that undergo programmed cell death such as thymocytes, dendritic cells, lymphocytes, macrophages and monocytes. There may also be some expression of functional P2X₇ receptors on erythrocytes.

“Non-functional P2X₇ receptor” generally refers to a form of a P2X₇ receptor having a conformation whereby the receptor is unable to form an apoptotic pore. One example arises where one or more of the monomers has a cis isomerisation at Pro210 (according to SEQ ID No:1). The isomerisation may arise in human and non human mammalian monomers from any molecular event that leads to misfolding of the monomer, including for example, mutation of monomer primary sequence or abnormal post translational processing. One consequence of the isomerisation is that the receptor is unable to bind to ATP at one or more ATP binding sites on the trimer and thereby extend the opening of the channel. In particular, where one of the three monomers is incorrectly packed and as a consequence, two ATP binding sites are disrupted. In the circumstances, the receptor cannot form a pore and this limits, the extent to which calcium ions may enter the cytosol. Only partial channel activity is maintained. Non-functional P2X₇ receptors are expressed on a wide range of epithelial and haematopoietic cancers.

“E200 epitope” generally refers to an epitope presented on a non-functional P2X₇ receptor. In humans the sequence is GHNYTTRNILPGLNITC (SEQ ID NO:3). In canines the sequence is GHNYTTRNILPDINITC (SEQ ID NO:4).

“E300 epitope” generally refers to an epitope presented on a non-functional P2X₇ receptor. In humans and canines the sequence is identical, namely: KYYKENNVEKRTLIKVF (SEQ ID NO:50).

“Composite epitope” generally refers to an epitope that is formed from the juxtaposition of the E200 and E300 epitopes. The point of difference in E200 as between canines and humans is not contained in the canine composite epitope, meaning that the canine and human composite epitopes are identical. While the feline P2X₇ receptor sequence has not been characterised, the serological data herein demonstrates that the feline composite epitope is identical or substantially the same as the canine and human composite epitope.

“Antibodies” or “immunoglobulins” or “Igs” are gamma globulin proteins that are found in blood, or other bodily fluids of verterbrates that function in the immune system to bind antigen, hence identifying and/or neutralizing foreign objects.

Antibodies are generally a heterotetrameric glycoprotein composed of two identical light (L) chains and two identical heavy (H) chains. Each L chain is linked to a H chain by one covalent disulfide bond. The two H chains are linked to each other by one or more disulfide bonds depending on the H chain isotype. Each H and L chain also has regularly spaced intrachain disulfide bridges.

H and L chains define specific Ig domains. More particularly, each H chain has at the N-terminus, a variable domain (V_(H)) followed by three constant domains (C_(H)) for each of the α and γ chains and four C_(H) domains for u and c isotypes. Each L chain has at the N-terminus, a variable domain (V_(L)) followed by a constant domain (C_(L)) at its other end. The V_(L) is aligned with the V_(H) and the C_(L) is aligned with the first constant domain of the heavy chain (C_(H)1).

Antibodies can be assigned to different classes or isotypes. There are five classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, having heavy chains designated α, δ, ε, γ, and μ, respectively. The γ and α classes are further divided into subclasses on the basis of relatively minor differences in C_(H) sequence and function, e.g., humans express the following subclasses: IgG1, IgG2, IgG3, IgG4, IgA1, and IgA2. The L chain from any vertebrate species can be assigned to one of two clearly distinct types, called kappa and lambda, based on the amino acid sequences of their constant domains.

The constant domain includes the Fc portion which comprises the carboxy-terminal portions of both H chains held together by disulfides. The effector functions of antibodies such as ADCC are determined by sequences in the Fc region, which region is also the part recognized by Fc receptors (FcR) found on certain types of cells.

The pairing of a V_(H) and V_(L) together forms a “variable region” or “variable domain” including the amino-terminal domains of the heavy or light chain of the antibody. The variable domain of the heavy chain may be referred to as “V_(H).” The variable domain of the light chain may be referred to as “V_(L).” The V domain contains an “antigen binding site” which affects antigen binding and defines specificity of a particular antibody for its particular antigen. V regions span about 110 amino acid residues and consist of relatively invariant stretches called framework regions (FRs) (generally about 4) of 15-30 amino acids separated by shorter regions of extreme variability called “hypervariable regions” (generally about 3) that are each generally 9-12 amino acids long. The FRs largely adopt a β-sheet configuration and the hypervariable regions form loops connecting, and in some cases forming part of, the β-sheet structure.

“Hypervariable region” refers to the regions of an antibody variable domain which are hypervariable in sequence and/or form structurally defined loops. Generally, antibodies comprise six hypervariable regions; three in the V_(H) (H1, H2, H3), and three in the V_(L) (L1, L2, L3).

“Framework” or “FR” residues are those variable domain residues other than the hypervariable region residues herein defined.

“A peptide for forming an antigen binding site” generally refers to a peptide that may form a conformation that confers the specificity of an antibody for antigen. Examples include whole antibody or whole antibody related structures, whole antibody fragments including a variable domain, variable domains and fragments thereof, including light and heavy chains, or fragments of light and heavy chains that include some but not all of hypervariable regions or constant regions.

An “antigen binding site” generally refers to a molecule that includes at least the hypervariable and framework regions that are required for imparting antigen binding function to a V domain. An antigen binding site may be in the form of an antibody or an antibody fragment, (such as a dAb, Fab, Fd, Fv, F(ab′)₂ or scFv) in a method described herein.

An “intact” or “whole” antibody is one which comprises an antigen-binding site as well as a C_(L) and at least heavy chain constant domains, C_(H)I, C_(H)2 and C_(H)3. The constant domains may be native sequence constant domains (e.g. human native sequence constant domains) or amino acid sequence variant thereof.

“whole antibody fragments including a variable domain” include Fab, Fab′, F(ab′)₂, and Fv fragments; diabodies; linear antibodies, single-chain antibody molecules; and multispecific antibodies formed from antibody fragments.

The “Fab fragment” consists of an entire L chain along with the variable region domain of the H chain (V_(H)), and the first constant domain of one heavy chain (C_(H)I). Each Fab fragment is monovalent with respect to antigen binding, i.e., it has a single antigen-binding site.

A “Fab′ fragment” differs from Fab fragments by having additional few residues at the carboxy terminus of the C_(H)I domain including one or more cysteines from the antibody hinge region. Fab′-SH is the designation herein for Fab′ in which the cysteine residue(s) of the constant domains bear a free thiol group.

A “F(ab)₂ fragment” roughly corresponds to two disulfide linked Fab fragments having divalent antigen-binding activity and is still capable of cross-linking antigen.

An “Fv” is the minimum antibody fragment which contains a complete antigen-recognition and binding site. This fragment consists of a dimer of one heavy and one light chain variable region domain in tight, non-covalent association.

In a single-chain Fv (scFv) species, one heavy and one light chain variable domain can be covalently linked by a flexible peptide linker such that the light and heavy chains can associate in a “dimeric” structure analogous to that in a two-chain Fv species. From the folding of these two domains emanate six hypervariable loops (3 loops each from the H and L chain) that contribute the amino acid residues for antigen binding and confer antigen binding specificity to the antibody.

“Single-chain Fv” also abbreviated as “sFv” or “scFv” are antibody fragments that comprise the V_(H) and V_(L) antibody domains connected to form a single polypeptide chain. Preferably, the scFv polypeptide further comprises a polypeptide linker between the V_(H) and V_(L) domains which enables the scFv to form the desired structure for antigen binding.

A “single variable domain” is half of an Fv (comprising only three CDRs specific for an antigen) that has the ability to recognize and bind antigen, although at a lower affinity than the entire binding site

“Diabodies” refers to antibody fragments with two antigen-binding sites, which fragments comprise a heavy-chain variable domain (V_(H)) connected to a light-chain variable domain (V_(L)) in the same polypeptide chain (V_(H)-V_(L)). The small antibody fragments are prepared by constructing sFv fragments (see preceding paragraph) with short linkers (about 5-10 residues) between the V_(H) and V_(L) domains such that interchain but not intra-chain pairing of the V domains is achieved, resulting in a bivalent fragment, i.e., fragment having two antigen-binding sites.

Diabodies may be bivalent or bispecific. Bispecific diabodies are heterodimers of two “crossover” sFv fragments in which the V_(H) and V_(L) domains of the two antibodies are present on different polypeptide chains. Triabodies and tetrabodies are also generally known in the art.

An “isolated antibody” is one, which has been identified and separated and/or recovered from a component of its pre-existing environment. Contaminant components are materials that would interfere with therapeutic uses for the antibody, and may include enzymes, hormones, and other proteinaceous or nonproteinaceous solutes.

“Monoclonal antibody” refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the animal antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts. Monoclonal antibodies are highly specific, being directed against a single antigenic site or determinant on the antigen. In addition to their specificity, the monoclonal antibodies are advantageous in that they may be synthesized uncontaminated by other antibodies. Monoclonal antibodies may be prepared by the hybridoma methodology. The “monoclonal antibodies” may also be isolated from phage antibody libraries using the techniques.

The monoclonal antibodies herein include “chimeric” antibodies in which a portion of the heavy and/or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, while the remainder of the chain(s) is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity.

The term “anti-P2X₇ receptor antibody” or “an antibody that binds to P2X₇ receptor” refers to an antibody that is capable of binding P2X₇ receptor with sufficient affinity such that the antibody is useful as a diagnostic and/or therapeutic agent in targeting P2X₇ receptor, typically non-functional P2X₇ receptor. Preferably, the extent of binding of an P2X₇ receptor antibody to an unrelated, P2X₇ receptor protein is less than about 10% of the binding of the antibody to P2X₇ receptor as measured, e.g., by a radioimmunoassay (RIA). In certain embodiments, an antibody that binds to P2X₇ receptor has a dissociation constant (Kd) of <1 μM, <100 nM, <10 nM, <1 nM, or <0.1 nM. An anti non-functional P2X₇ receptor antibody is generally one having some or all of these serological characteristics and that binds to non-functional P2X₇ receptors but not to functional P2X₇ receptors.

An “affinity matured” antibody is one with one or more alterations in one or more hypervariable region thereof, which result in an improvement in the affinity of the antibody for antigen, compared to a parent antibody, which does not possess those alteration(s). Preferred affinity matured antibodies will have nanomolar or even picomolar affinities for the target antigen. Affinity matured antibodies are produced by procedures known in the art.

A “blocking” antibody” or an “antagonist” antibody is one, which inhibits or reduces biological activity of the antigen it binds. Preferred blocking antibodies or antagonist antibodies substantially or completely inhibit the biological activity of the antigen.

An “agonist antibody”, as used herein, is an antibody which mimics at least one of the functional activities of a polypeptide of interest.

“Binding affinity” generally refers to the strength of the sum total of noncovalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). Unless indicated otherwise, as used herein, “binding affinity” refers to intrinsic binding affinity, which reflects a 1:1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (K_(d)). Affinity can be measured by common methods known in the art, including those described herein. Low-affinity antibodies generally bind antigen slowly and tend to dissociate readily, whereas high-affinity antibodies generally bind antigen faster and tend to remain bound longer. A variety of methods of measuring binding affinity are known in the art, any of which can be used for purposes of the present invention.

‘Treatment’ generally refers to both therapeutic treatment and prophylactic or preventative measures.

Animals requiring treatment include those already having a benign, pre-cancerous, or non-metastatic tumor as well as those in which the occurrence or recurrence of cancer is to be prevented.

The objective or outcome of treatment may be to reduce the number of cancer cells; reduce the primary tumor size; inhibit (i.e., slow to some extent and preferably stop) cancer cell infiltration into peripheral organs; inhibit (i.e., slow to some extent and preferably stop) tumor metastasis; inhibit, to some extent, tumor growth; and/or relieve to some extent one or more of the symptoms associated with the disorder.

Efficacy of treatment can be measured by assessing the duration of survival, time to disease progression, the response rates (RR), duration of response, and/or quality of life.

In one embodiment, the method is particularly useful for extending time to disease progression.

In one embodiment, the method is particularly useful for extending survival of the animal, including overall survival as well as progression free survival.

In one embodiment, the method is particularly useful for providing a complete response to therapy whereby all signs of cancer in response to treatment have disappeared. This does not always mean the cancer has been cured.

In one embodiment, the method is particularly useful for providing a partial response to therapy whereby there has been a decrease in the size of one or more tumors or lesions, or in the extent of cancer in the body, in response to treatment.

“Pre-cancerous” or “pre-neoplasia” generally refers to a condition or a growth that typically precedes or develops into a cancer. A “pre-cancerous” growth may have cells that are characterized by abnormal cell cycle regulation, proliferation, or differentiation, which can be determined by markers of cell cycle.

“A condition or symptom associated” [with the cancer] may be any pathology that arises as a consequence of, preceding, or proceeding from, the cancer. For example, where the cancer is a skin cancer, the condition or relevant symptom may be microbial infection. Where the cancer is a secondary tumor, the condition or symptom may relate to organ dysfunction of the relevant organ having tumor metastases. In one embodiment, the methods of treatment described herein are for the minimisation or treatment of a condition or symptom in an animal that is associated with a cancer in the animal.

A “non self” molecule, such as a “non self” antigen binding site, or “non self” antibody generally refers to a molecule that has been produced outside of, or exogenous to, a body in which the molecule is to be provided, for example, for treatment. As an example, synthetic or recombinant molecules are “non self”. Further, a molecule that is generated in one animal and administered to another animal for treatment is “non self”. “Non self” antigen binding sites and antibodies may be used in accordance with the invention for adoptive transfer of immunity, for example, as occurs in antibody infusion. In contrast, a molecule that is generated inside an animal that is to be treated with that molecule, is generally a “self” or “endogenous” molecule. One example of a “self” molecule is an antigen binding site or antibody that is generated, or arises from an adaptive immune response to immunogen.

“level of non self antigen binding sites in circulation” in the animal generally refers to the concentration of antigen binding site in a body fluid, preferably peripheral blood.

a “substantially undetectable level of non self antigen binding sites in circulation” generally refers to a concentration of exogenous antigen binding sites (i.e. those that have been administered by adoptive transfer) that is at least half of the concentration of the antigen binding sites in circulation at the time of administration of the antigen binding sites, preferably 25%, or 10%, or 5% or 1% of said concentration, or otherwise less than 0.001 mg/kg of the animal. The phrase may also refer to a circumstance where antigen binding sites that have been given for the purpose of cancer immunotherapy cannot be detected at all.

a cancer that is “substantially undetectable” generally refers to a circumstance where therapy has depleted the size, volume or other physical measure of a cancer so that using relevant standard detection techniques such as in vivo imaging, the cancer, as a consequence of the therapy, is not clearly detectable. The phrase also refers to the circumstance where the cancer cannot be detected at all.

“forming an immune response” generally refers to invoking or inducing antigen specific immunity via the adaptive immune system. As is generally understood in the art, induction of antigen specific immunity is distinguished from adoptive transfer of immunity, standard cancer immunotherapy by administration of exogenous or non self antibody being one example of the latter.

B. Cancer Immunotherapy by Antibody Infusion

While the tissue expression profile of non functional P2X₇ receptors in normal, pre-neoplastic and neoplastic human tissues was understood at the time of the invention, very little was known regarding the tissue expression of non functional P2X₇ receptors in non human animals, especially companion animals such as cats and dogs.

In particular, it was not known whether the trimeric non functional receptor is expressed on living tissue in companion animals and in particular in which tissues. Further, it was not known whether expression would be found on cancer tissues and if so to what extent expression would be limited to cancer tissues. Accordingly it was not known whether certain companion animal cancers express non functional P2X₇ receptor, nor whether treatment with antibodies would have significant toxicity for normal cells.

Further, it was not known whether the cancer-specific epitopes observed in humans on living cancer tissue are present on cancer tissue in companion animals. At the time of the invention, this was directly relevant to the question of how to generate anti-cancer antibodies in companion animals. In particular, the cat P2X₇ receptor sequence was not known at all.

The dog P2X₇ sequence was known to be significantly different from the human P2X₇ receptor at the region of the dog sequence corresponding with E200 in the human, where immediately carboxyl to the key proline-210 (known in the human to give rise to non functionality of the human receptor), the dog sequence was known to have a non conservative substitution of negatively charged aspartate for neutral glycine as in the human. Further, of the other amino acid differences as between dog and human, at least about 55% of these were known to be non conservative substitutions, and one insertion not found in human. See in particular FIG. 2.

In summary of the above, at the time of the invention it was not known whether non functional P2X₇ receptors existed in companion animals including dogs and cats and therefore not known whether P2X₇ receptors could be used as a biomarker for treatment of cancer in companion animals as it has been used for humans.

As described herein, the inventors have shown that sheep antibodies raised: against an immunisation with a peptide having the E200 epitope are highly effective for treatment of a wide variety of cancers having a higher incidence in companion animals and with minimal side effects or toxicity. From this the inventors have recognised that certain live cancer cells in dogs and cats express non functional P2X₇ receptors. Given minimal toxicity, the expression of these, receptors appears to be limited to pre neoplastic or neoplastic tissues. Further, and in spite of differences, for example as between the dog and human P2X₇ sequences, these companion animal receptors seem to have an extracellular conformation much like that on which the human E200 epitope has been found.

Further, and surprisingly, the inventors have recognised that xenogeneic antibodies raised against xenogeneic P2X₇ immunogen are highly effective for treating cancer in companion animals including cats and dogs.

Thus, in a first aspect the invention provides a method for minimising the progression of cancer in a companion animal, the method including the steps of:

-   -   providing a companion animal in which the progression of cancer         is to be minimised; and     -   providing in the animal a whole antibody, or a fragment thereof         including a variable domain for binding to a non functional P2X₇         receptor that is expressed by the animal;

thereby minimising the progression of cancer in the animal.

In a further aspect the invention provides a use of a whole antibody, or a fragment thereof including a variable domain for binding to a non functional P2X₇ receptor in the manufacture of a medicament for treatment of cancer in a companion animal.

In yet a further aspect the invention provides a use of a whole antibody, or a fragment thereof including a variable domain for binding to a non functional P2X₇ receptor for treatment of cancer in a companion animal.

An animal to be treated in accordance with the methods of the first aspect of the invention may be one that has received, or is to receive any one of the therapeutic antibodies indicated for oncology.

In one embodiment of the first aspect, the antigen binding site of an antibody may be one that discriminates between functional and non-functional P2X₇ receptors, so as to bind to non-functional receptors, but not to functional receptors. Examples of these antigen binding sites are those that bind to the E200 epitope, E300 epitope or composite epitope as for example in PCT/AU2002/000061, PCT/AU2002/001204, PCT/AU2007/001540, PCT/AU2007/001541, PCT/AU2008/001364, PCT/AU2008/001365, PCT/AU2009/000869 and PCT/AU2010/001070, all of which are incorporated by reference.

The antigen binding site may take the form of a whole antibody, or a whole antibody fragment such as a Fab, a Fab′, a F(ab′)₂, and Fv, a single chain Fv, or a single variable domain.

The antigen binding site may be syngeneic, allogeneic or xenogeneic with respect to the companion animal that is to receive it for treatment of cancer.

Typically the antigen binding site is non self or exogenous meaning that it has been found or isolated outside of the animal who is treated according to the methods of the invention.

The antigen binding site may be affinity matured.

The antigen binding site may have multiple specificities or valencies.

The antigen binding site may be adapted so as to be suited to administration by a selected method.

The antibody may be a whole antibody of any isotype. The antibody may be one obtained from monoclonal or polyclonal antisera. The antibody may be produced by hybridoma, or by recombinant expression, or may be obtained from serum for example as obtainable from a mammal, particularly a human or mouse. The antibody may also be obtained from an avian.

The antibody may be chimeric, i.e. one containing human variable domains and non human constant domains. Alternatively, it may be humanized, i.e. one formed by grafting non human CDRs onto a human antibody framework. Still further, the antibody may be fully human.

The antibody may be modified with respect to effector function, so as to enhance, e.g., the effectiveness of the antibody in treating cancer.

Where the antibody is an antibody fragment, the antibody fragment is selected from the group consisting of a dAb, Fab, Fd, Fv, F(ab′)₂, scFv and CDR.

Dosage amount, dosage frequency, routes of administration etc are described in detail below.

Methods of preparing and administering antibodies to an animal in need thereof are well known to, or are readily determined by those skilled in the art. The route of administration may be, for example, oral, parenteral (e.g. intravenous, intraarterial, intraperitoneal, intramuscular, subcutaneous, intradermal, rectal or vaginal), by inhalation or topical. One form for administration would be a solution for injection, in particular for intravenous or intraarterial injection or drip, comprising a buffer (e.g. acetate, phosphate or citrate buffer), a surfactant (e.g. polysorbate), optionally a stabilizer agent (e.g. albumin). In other methods antibodies can be delivered directly to the site of disease thereby increasing the exposure of the diseased cell or tissue to the antibody.

Preparations for parenteral administration includes sterile aqueous (aqueous carriers include water, alcoholic/aqueous solutions, emulsions or suspensions, including saline and buffered media) or non-aqueous (non-aqueous solvents are propylene glycol, polyethylene glycol, vegetable oils such as olive oil, and injectable organic esters such as ethyl oleate) solutions, suspensions, and emulsions. Pharmaceutically acceptable carriers include 0.01-0.1M and preferably 0.05M phosphate buffer or 0.9% saline. Other common parenteral vehicles include sodium phosphate solutions, Ringer's dextrose, dextrose and sodium chloride, lactated Ringer's, or fixed oils. Intravenous vehicles include fluid and nutrient replenishers, electrolyte replenishers, such as those based on Ringer's dextrose, and the like. Preservatives and other additives may also be present such as for example, antimicrobials, antioxidants, chelating agents, and inert gases and the like.

More particularly, pharmaceutical compositions suitable for injectable use include sterile aqueous solutions (where water soluble) or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions, in such cases, the composition must be sterile and should be fluid to the extent that easy syringability exists. It should be stable under the conditions of manufacture and storage and will preferably be preserved against the contaminating action of microorganisms, such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (e.g., glycerol, propylene glycol, and liquid polyethylene glycol, and the like), and suitable mixtures thereof. The proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Suitable formulations for use in the therapeutic methods disclosed herein are described in Remington's Pharmaceutical Sciences, Mack Publishing Co., 16th ed. (1980).

Prevention of the action of microorganisms can be achieved by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars, polyalcohols, such as mannitol, sorbitol, or sodium chloride in the composition. Prolonged absorption of the injectable compositions can be brought about by including in the composition an agent which delays absorption, for example, aluminium monostearate and gelatin.

In any case, sterile injectable solutions can be prepared by incorporating an active compound (e.g., antigen binding site) in the required amount in an appropriate solvent with one or a combination of ingredients enumerated herein, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle, which contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum drying and freeze-drying, which yields a powder of an active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof. The preparations for injections are processed, filled into containers such as ampoules, bags, bottles, syringes or vials, and sealed under aseptic conditions according to methods known in the art. Further, the preparations may be packaged and sold in the form of a kit. Such articles of manufacture will preferably have labels or package inserts indicating that the associated compositions are useful for treating a subject suffering from, or predisposed disorders.

Effective doses of the compositions of the present invention, for treatment of disorders as described herein vary depending upon many different factors, including means of administration, target site, physiological state of the patient, whether the patient is human or an animal, other medications administered, and whether treatment is prophylactic or therapeutic. Treatment dosages may be titrated using routine methods known to those of skill in the art to optimize safety and efficacy.

For treatment of certain disorders with an antibody, the dosage can range, e.g., from about 0.0001 to 100 mg/kg, and more usually 0.01 to 5 mg/kg (e.g., 0.02 mg/kg, 0.25 mg/kg, 0.5 mg/kg, 0.75 mg/kg, 1 mg/kg, 2 mg/kg, etc.), of the host body weight. For example dosages can be 1 mg/kg body weight or 10 mg/kg body weight or within the range of 1-10 mg/kg, preferably at least 1 mg/kg. Doses intermediate in the above ranges are also intended to be within the scope of the invention. Subjects can be administered such doses daily, on alternative days, weekly or according to any other schedule determined by empirical analysis. An exemplary treatment entails administration in multiple dosages over a prolonged period, for example, of at least six months. Additional exemplary treatment regimes entail administration once per every two weeks or once a month or once every 3 to 6 months. Exemplary dosage schedules include 1-10 mg/kg or 15 mg/kg on consecutive days, 30 mg/kg on alternate days or 60 mg/kg weekly. In some methods, two or more antigen binding sites with different binding specificities are administered simultaneously, in which case the dosage of each antigen binding sites administered falls within the ranges indicated.

The antibody for binding to a non-functional P2X₇ receptor expressed on a cell can be administered on multiple occasions. Intervals between single dosages can be weekly, monthly or yearly. Intervals can also be irregular as indicated by measuring blood levels of target polypeptide or target molecule in the patient. In some methods, dosage is adjusted to achieve a plasma polypeptide concentration of 1-1000 ug/mL and in some methods 25-300 ug/mL. Alternatively, the antibody can be administered as a sustained release formulation, in which case less frequent administration is required. Dosage and frequency vary depending on the half-life of the antibody in the patient. The half-life of an antibody can also be prolonged via fusion to a stable polypeptide or moiety, e.g., albumin or PEG. In general, humanized antibodies show the longest half-life, followed by chimeric antibodies and nonhuman antibodies. In one embodiment, the antibody can be administered in unconjugated form. In another embodiment the antibody can be administered multiple times in conjugated form. In certain therapeutic applications, a relatively high dosage (e.g., up to 400 mg/kg of anti P2X₇ binding molecule, e.g., antibody per dose), at relatively short intervals is sometimes required until progression of the disease is reduced or terminated, and preferably until the patient shows partial or complete amelioration of symptoms of disease. The amounts can be several logs lower (i.e. 2 to 3 logs lower) where the antibody is conjugated to a radioisotope or cytotoxic drug.

Therapeutic agents can be administered by parenteral, topical, intravenous, oral, subcutaneous, intraarterial, intracranial, intraperitoneal, intranasal or intramuscular means for prophylactic and/or therapeutic treatment, in some methods, agents are injected directly into a particular tissue where non-functional P2X₇ receptor cells have accumulated, for example intracranial injection. Intramuscular injection or intravenous infusion are preferred for administration of antibody.

An antibody can optionally be administered in combination with other agents that are effective in treating the disorder or condition in need of treatment (e.g., prophylactic or therapeutic). Examples are agents commonly used for chemotherapy or radiotherapy in oncology. Additionally or alternatively, the antibody or agent may be administered before, during or after surgical intervention for resection or removal of tumor or tissue.

In accordance with the first aspect of the invention, in one embodiment, the method may be for treatment of cancer, especially for a therapeutic treatment of cancer.

In one embodiment, the objective or outcome of treatment is one or more of:

-   -   to reduce the number of cancer cells;     -   reduce the primary tumor size;     -   inhibit (i.e., slow to some extent and preferably stop) cancer         cell infiltration into peripheral organs;     -   inhibit (i.e., slow to some extent and preferably stop) tumor         metastasis;     -   inhibit, to some extent, tumor growth;     -   relieve to some extent one or more of the symptoms associated         with the disorder.

In one embodiment, the method of the first aspect of the invention is for extending time to disease progression.

In one embodiment, the method of the first aspect is for extending survival of the animal, including overall survival as well as progression free survival.

In one embodiment, the method of the first aspect is for providing a complete response to therapy whereby all signs of cancer in response to treatment have disappeared.

In one embodiment, the method of the first aspect is for providing a partial response to therapy whereby there has been a decrease in the size of one or more tumors or lesions, or in the extent of cancer in the body, in response to treatment.

In one embodiment, animals requiring treatment include those having a benign, pre-cancerous, non-metastatic tumor.

In one embodiment, the cancer is pre-cancerous or pre-neoplastic.

In one embodiment, the cancer is a secondary cancer or metastases. The secondary cancer may be located in any organ or tissue, and particularly those organs or tissues having relatively higher hemodynamic pressures, such as lung, liver, kidney, pancreas, bowel and brain.

In one embodiment, the cancer may be substantially undetectable.

The companion animal may be a cat or dog. However, in light of the cross reactivity of antibodies raised against human protein for non primate receptors, the inventors have recognised that other non human mammals having equally distant phylogeny from humans would benefit from the invention. In one embodiment the companion animal is a high value animal or thoroughbred. One example is a horse.

Typically the cancer or pre-cancer requiring treatment is one that has a higher incidence in a given companion animal. For example, where the companion animal is a dog, the cancer may be lymphoma, mast cell tumor, soft tissue sarcoma, hemangiosarcoma, osteosarcoma, squamous cell carcinoma, mammary carcinoma, melanoma, histiocytoma, spindle cell carcinoma or fibrosarcoma.

Where the companion animal is a cat, the cancer may be a lymphoma, mast cell tumor, squamous cell carcinoma, mammary carcinoma, hemangiosarcoma, osteosarcoma, fibrosarcoma, or sebaceous hyperplasia/adenoma.

Other examples of cancer are described in Table I or include blastoma (including medulloblastoma and retinoblastoma), sarcoma (including liposarcoma and synovial cell sarcoma), neuroendocrine tumors (including carcinoid tumors, gastrinoma, and islet cell cancer), mesothelioma, schwannoma (including acoustic neuroma), meningioma, adenocarcinoma, melanoma, leukemia or lymphoid malignancies, lung cancer including small-cell lung cancer (SGLG), non-small cell lung cancer (NSGLG), adenocarcinoma of the lung and squamous carcinoma of the lung, cancer of the peritoneum, hepatocellular cancer, gastric or stomach cancer including gastrointestinal cancer, pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, liver cancer, bladder cancer, hepatoma, breast cancer (including metastatic breast cancer), colon cancer, rectal cancer, colorectal cancer, endometrial or uterine carcinoma, salivary gland carcinoma, kidney or renal cancer, prostate cancer, vulval cancer, thyroid cancer, hepatic carcinoma, anal carcinoma, penile carcinoma, testicular cancer, esophagael cancer, tumors of the biliary tract, as well as head and neck cancer.

The dosage and frequency of administration can vary depending on whether the treatment is prophylactic or therapeutic. In prophylactic applications, compositions comprising antibodies or a cocktail thereof are administered to a patient not already in the disease state or in a pre-disease state to enhance the patient's resistance. Such an amount is defined to be a “prophylactic effective dose.” In this use, the precise amounts again depend upon the animal's state of health and general immunity, but generally range from 0.1 to 25 mg per dose, especially 0.5 to 2.5 mg per dose. A relatively low dosage is administered at relatively infrequent intervals over a long period of time. Some animals continue to receive treatment for the rest of their lives.

In therapeutic applications, a relatively high dosage (e.g., from about 1 to 400 mg/kg of binding molecule, e.g., antibody per dose, with dosages of from 5 to 25 mg being more commonly used for radioimmunoconjugates and higher doses for cytotoxin-drug conjugated molecules) at relatively short intervals is sometimes required until progression of the disease is reduced or terminated, and preferably until the animal shows partial or complete amelioration of symptoms of disease.

In one embodiment, the antibody is provided in combination with another chemotherapeutic or anti-neoplastic compound indicated for use for the relevant cancer in the companion animal requiring treatment. Examples of these compounds and relevant indication are described in Table 1.

In another embodiment, the antibody is provided prior to, during, or post a clinical intervention selected from the group consisting of surgery, radiation therapy, hyperthermia therapy, photodynamic therapy, chemotherapy, gene therapy and immunotherapy.

C. Cancer Immunotherapy by Immunisation

In a second aspect the invention provides a method for minimising the progression of cancer in a companion animal, the method including the steps of:

-   -   providing a companion animal requiring treatment for cancer; and     -   forming an immune response in the companion animal to a         non-functional P2X₇ receptor;

thereby minimising the progression of cancer in the companion animal.

In a third aspect the invention provides a method for minimising the progression of cancer in a companion animal that has received a non self antigen binding site for treatment of the cancer, the method including the steps of:

-   -   providing a companion animal that has received a non self         antigen binding site for treatment of the cancer;     -   forming an immune response in the companion animal to a         non-functional P2X₇ receptor;

thereby minimising the progression of cancer in the companion animal.

In a further aspect, the invention provides a use of a non-functional P2X₇ receptor or fragment thereof in the manufacture of a medicament for treatment of a cancer in a companion animal, especially an animal such as a cat or dog that has received a non self antigen binding site for treatment of the cancer.

In yet a further aspect, the invention provides a use of a non-functional P2X₇ receptor or fragment thereof for treatment of a cancer in a companion animal, especially an animal such as a cat or dog that has received a non self antigen binding site for treatment of the cancer.

In another aspect, the invention provides a use of a P2X₇ receptor or fragment thereof in the manufacture of a medicament for the treatment of, or for the inhibition of progression of cancer in a companion animal that has received an anti-non-functional P2X₇ receptor antigen binding site for treatment of the cancer.

In one embodiment of the second and third aspects of the invention, the companion animal may not have detectable non self antigen binding sites in circulation at the time that the immune response is formed in the companion animal. For example, infused antibody may have been cleared from plasma at the time of immunisation. Further, the companion animal may not have detectable cancer at the time that the immune response is formed in the companion animal, for example, the cancer may have substantially diminished in size, mass or other physical measure as a consequence of administration of an antigen binding site to the companion animal at the time that the immune response is formed in the companion animal.

In accordance with the second and third aspects of the invention, the immune response may be formed by an immunogen. The immunogen may be provided in the form of a P2X₇ receptor, or a fragment of a P2X₇ receptor that is capable of inducing an immune response to a non-functional P2X₇ receptor in the companion animal. A non-functional P2X₇ receptor is defined as having at least one of the three ATP binding sites that are formed at the interface between adjacent correctly packed monomers that are unable to bind ATP. Such receptors are unable to extend the opening of the non-selective calcium channels to apoptotic pores. The immunogen may contain at least one sequence that is capable of being presented on a major histocompatibility complex class II molecule and/or is capable of interacting with a T or B-cell receptor or a B-cell membrane bound-immunoglobulin. Typically, the companion animal is a cat or dog, in which case the immunogen is provided in the form of a cat or dog P2X₇ receptor, or fragment thereof that is capable of inducing an immune response to a P2X₇ receptor. A dog P2X₇ receptor sequence is shown in FIG. 2 herein. Typically the immune response that is formed in the companion animal is specific for non-functional P2X₇ receptors, in which case antibodies or cellular components that are reactive with non-functional P2X₇ receptors (i.e. non ATP binding receptors), but not reactive with functional P2X₇ receptors (i.e. ATP binding receptors are) are formed in the companion animal.

In a preferred form of the second and third aspects of the invention, the immunogen is provided in an initial administration to the companion animal, thereby forming a response that includes IgM production. In a further preferred form, the immunogen, which has been provided in an initial administration to the companion animal, thereby forming a response that includes IgM production, is administered at a later time, in a further administration to the initial administration, thereby forming a response that includes IgG production. In this embodiment, typically the further administration of immunogen occurs when the level of IgM in circulation in the companion animal is substantially undetectable.

The immune response formed in accordance with the second and third aspects of the invention may be a humoral and/or cellular response. A humoral response may include the transformation of B-cells into plasma cells that secrete antibody, Th2 activation and cytokine production, germinal centre formation and isotype switching, affinity maturation of B-cells and/or memory cell generation. A cellular response may include activating antigen-specific cytotoxic T-lymphocytes, activating macrophages and natural killer cells and/or stimulating cells to secrete cytokines. The humoral and/or cellular response formed in the companion animal may treat or ameliorate a cancer in the companion animal, or minimise the progression of cancer in the companion animal.

In the above described embodiments of the second and third aspects of the invention, the antigen binding sites received by the companion animal may be reactive with any biomarker that is associated with cancer. Examples include antigen binding sites against P2X₇, especially, non-functional P2X₇, against VEGF, especially VEGF A, C or D, Her-2, CD20 or others. Typically the antigen binding sites received by the companion animal are reactive with P2X₇ receptor, especially a non-functional P2X₇ receptor.

In another embodiment of the second and third aspects of the invention, there is provided a composition for treating, or for inhibiting the progression of a cancer in a companion animal including a P2X₇ receptor or fragment thereof. Preferably the composition further includes a carrier, excipient or diluent. Preferably, the composition further includes an adjuvant. In a preferred form, the composition enables the formation of a primary immune response (including IgM production) upon initial administration of the immunogen to the companion animal, and a second immune response (including IgG production) upon administration of the immunogen further to the initial administration.

Without being bound by any theory or mode of action, it is believed that the above described embodiments relevant to the second and third aspects of the invention provide an alternative and/or improved treatment regime for the reason that endogenous immune components such as antibodies and antigen specific cells that arise from immunisation provide for a more prolonged and higher exposure of cell surface P2X₇ receptors after administration of antigen binding sites has been completed and the circulating level of non self anti-P2X₇ antigen binding sites becomes undetectable. Further, it is believed that P2X₇ receptor crowding, as arises when high concentrations of non self or exogenous antibodies are provided in a companion animal, minimises the level of specific antibody binding to the key P2X₇ epitopes that provide for an anti cancer immune response, thereby limiting the efficacy of immunotherapy. The inventors have found that immunisation of a companion animal at a time when the circulating level of non self antibodies becomes substantially undetectable avoids receptor crowding, and this improves the efficacy of immunotherapy, particularly at a time when cancer in the companion animal may be substantially undetectable.

In one embodiment of the second and third aspects of the invention, the animals selected for treatment have not been treated with antibody immunotherapy or other form of therapy. In another embodiment, the animals selected for treatment according to a method described above are those who have received, or who are continuing to receive antibody immunotherapy, for treatment of cancer. Antibody immunotherapy generally means the administration of exogenous, (otherwise known as or “non self”) antibodies to an animal requiring treatment, as in the case of adoptive transfer of antibody. For example, the animal may have received any one of the therapeutic antibodies that have received regulatory approval for indications related to oncology. Avastin, Herceptin, Rituxan are examples. Typically the animal has received or is continuing to receive an anti P2X₇ receptor antibody. Examples of suitable anti-P2X₇ antibodies, their generation, manufacture, use and administration to a companion animal are described in the embodiments relevant to the first aspect of the invention.

Further, the animal selected for treatment according to the second and third aspects of the invention may or may not have detectable cancer at the time of treatment. Where the animal does not have detectable cancer, a primary or secondary humoral response is more easily detected because, with the cancer being present in substantially undetected amount, there is very little non-functional P2X₇ receptor available to remove IgM or IgG from body fluid.

The types of cancer which may be treated according to the second and third aspects of the invention and the desired treatment outcomes are those as described in the embodiments relevant to the first aspect of the invention.

The purpose of the treatment according to the second and third aspects of the invention is to at least minimise the progression of cancer by induction or formation of an immune response in the animal to a P2X₇ receptor. Therefore, the animal selected for treatment must be capable of generating an immune response sufficient for meeting this purpose. Generally the desired immune response includes a capacity to produce either or both of circulating IgM and IgG when the animal is challenged by cancer, as in recurrence of cancer.

Animals having a capacity to generate the immune response described herein may be selected or screened by a variety of methods well known in the art for detection of immunodeficiency. Typically, the animal selected for treatment will be one having at least one white blood cell component count within normal parameters. For example, a cat for inclusion is generally one having a white blood cell count of between 5.5 to 19.0×10⁹/L, or a lymphocyte count of between 0.9 to 7.0×10⁹/L. Neutrophil count may be between 2−13×10⁹/L; monocyte count <0.7×10⁹/L, eosinophil less than about 1.1×10⁹/L and basophil less than about 0.1×10⁹/L. For example, a dog for inclusion is generally one having a white blood cell count of between 4.5 to 17.0×10⁹/L, or a lymphocyte count of between 0:9 to 3.5×10⁹/L. Neutrophil count may be between 3.5-12×10⁹/L; monocyte count <1.2×10⁹/L, eosinophil less than about 1.5×10⁹/L and basophil less than about 0.1×10⁹/L.

It will be understood that in certain embodiments the cell count for any one of these blood cell components may fall outside these stated ranges, particularly in circumstances where the animal has a form of blood cancer, for example CML, CLL etc.

Generally an important factor is the lymphocyte count and/or monocyte count. In more detail, where either or both of these counts are significantly below the stated ranges for these components, the animal may be less likely to respond to administration of the immunogen.

Where the animal is continuing to receive antibody immunotherapy, in one embodiment of the second and third aspects of the invention, the antibody immunotherapy is allowed to continue to the desired clinical endpoint. Typically the desired clinical endpoint is a reduction of cancer to substantially undetectable levels. During, or at the completion of immunotherapy, the capacity of the animal to form, or generate an immune response to a P2X₇ receptor is then assessed. Where the assessment reveals that the animal is likely to benefit from immunisation with P2X₇ immunogen, the animal is then administered with immunogen.

In a preferred form of the second and third aspects of the invention, the level of non self or exogenous antigen binding sites in circulation in the animal arising from antibody immunotherapy is substantially undetectable at the time that the immune response is formed in the animal. Importantly, a key finding of the inventor is that efficacy of antibody treatment, particularly when cancer cells are in very low copy number, or otherwise substantially undetectable, decreases at higher circulating concentrations of antigen binding sites. This is believed to be a function of the low copy number of non-functional P2X₇ receptors on cancer cells relative to the high concentration of antigen binding sites that arise in standard antibody immunotherapy. Specifically, in the Examples herein, the inventor has found that as the circulatory level of antigen specific binding sites increase, and the number of cancer cells decrease, there is a much higher likelihood of crowding of the non-functional P2X₇ receptor by antigen binding sites that block antigen specific binding of the receptor. This blockage increases the likelihood that the intended cytotoxic, apoptotic or other effects of antigen specific binding by an antigen binding site will not be possible. One can determine the level of exogenous antigen binding sites in circulation by any standard serological technique capable of detecting antibody in fluid, one preferred example being ELISA using an antibody to capture antigen binding sites.

Further to the above, while not wanting to be bound by hypothesis, the inventors consider that administration of immunisation at a time where infused antibody is present increases the risk that the infused antibody could bind to the immunogen, resulting in immune complex formation and clearance, thereby avoiding antigen presentation and induction of antigen specific immunity. Therefore, in certain embodiments it is particularly useful to wait until the level of non self or exogenous antigen binding sites have been cleared from circulation before induction of the antigen specific immune response to immunogen.

The methods of the second and third aspects of the invention described herein require the formation of an immune response in an animal to be treated to a P2X₇ receptor, especially a non-functional P2X₇ receptor. Generally the immunogen, which is used for the purpose, is one which elicits an immune response to non-functional P2X₇ but not to functional P2X₇ receptors.

The inventors have found that the composite epitope exists in a wide range of species meaning (i) that antigen binding sites or antibodies could be raised in a wide range of animals for use in antibody infusion therapy and (ii) that a wide range of species of animals could be treated by the active immunisation therapy, according to the second and third aspects of the invention herein. The following table demonstrates the % identity as between the human composite epitope and the epitope in other species.

TABLE 2 Human E200/E300 Alignment to Other Species E200/E300 Species DNA Database No. Sequence Percent Identity Human AB590390.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Chimp XM_001163832.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Macaque AB173225.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Orangutan XM_002823877.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Marmoset XM_002753098.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Rabbit XM_002719745.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Horse XM_001495572.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Wolf NM_001113456.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Panda XM_002913118.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Boar AY691687.1 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Pig CT737324.4 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) Mouse NM_001038845.2 GHNYTTRNILPG-- 100% (SEQ ID NO: 6) AKYYKENNVEK (SEQ ID NO: 7) G. Pig NM_001173107.1 GHNYTTRNILPG--  96% (22/23) (SEQ ID NO: 6) AKYYRENNVEK (SEQ ID NO: 27) Bovine XM_591410.2 GHNYTTRNILPG--  96% (22/23) (SEQ ID NO: 6) AKYYKENNTEK (SEQ ID NO: 29) Rat NM_019256.1 GHNYTTRNILPG--  91% (21/23) (SEQ ID NO: 6) AKYYKENGMEK (SEQ ID NO: 31)

The immunogen may include or consist of a peptide including a sequence of a P2X₇ receptor. The peptide may contain at least one sequence that is capable of being presented on a major histocompatibility complex class II molecule or, that is capable of interacting with a B-cell receptor or a B-cell membrane bound-immunoglobulin. Typically the peptide includes a sequence of a non human, preferably companion animal P2X₇ receptor or fragment thereof.

A range of peptide immunogens are known and discussed in PCT/AU2002/000061, PCT/AU2002/000061, PCT/AU2008/001364 and PCT/AU2009/000869, the contents of which are incorporated in entirety.

Exemplary peptides immunogens within these specifications which include epitopes for generating an immune response to a non-functional P2X₇ receptor are described below.

PCT application Peptide immunogen sequence PCT/AU2002/000061, GHNYTTRNILPGLNITC (SEQ ID NO: 3) PCT/AU2008/001364 KYYKENNVEKRTLIKVF (SEQ ID NO: 50) PCT/AU2009/000869 GHNYTTRNILPGAGAKYYKENNVEK (SEQ ID NO: 32)

As discussed above, in one embodiment the peptide immunogen includes part or all of a canine or feline P2X₇ receptor sequence.

It will be understood that these are merely examples of possible immunogens useful for forming an immune response according to the second and third aspects of the invention. Further, the invention includes the use of other peptides as described in these applications useful for forming an immune response to non-functional P2X₇ receptors.

Typically the immunisation regime involves 2 or more immunisations. In a first immunisation, the objective may be to develop an IgM response to immunisation. A second immunisation may be to develop and IgG response. Further immunisations may be to boost the IgG response.

Where the immunogen is a peptide, the peptide may be provided in an amount of about 0.1 to 1 mg per administration, preferably about 0.25 to 0.75 mg, preferably about 0.5 mg in a large dog but half that in a small dog or cat.

A further administration of about 0.3 mg peptide may be applied as a boost in a large dog but half that in a small dog or a cat.

In one embodiment of the second and third aspects of the invention, a first immunisation is performed when the circulating level of antigen binding sites that had been administered for antibody immunotherapy is substantially undetectable. In other words, circulating antibody to the relevant cancer biomarker cannot be detected in peripheral blood. The level of IgM production is then monitored over the following weeks. At about 4 to 5 weeks after first immunisation, the level of IgM antibody is likely to have decreased to negligible circulating levels. At this point, a second immunisation is then performed and the level of IgG production is monitored over the following weeks. Further testing of immunity over the following months/years may be performed and boosting immunisations may be provided as required.

As discussed above, the immune response may target a biomarker that is different to the biomarker that has been targeted by antibody immunotherapy. For example, anti CD20 antibody may be used for antibody immunotherapy and a non-functional P2X₇ immunogen used for generating an immune response.

In another embodiment of the second and third aspects of the invention, a single biomarker is targeted by antibody immunotherapy and immunisation. For example, a monoclonal antibody directed to one epitope on a P2X₇ receptor (such as the E300 epitope) may be used for antibody immunotherapy, and an immunogen for forming an immune response that targets a different epitope (such as the E200 epitope) on P2X₇ may be used for immunisation.

A peptide immunogen for use in the second and third aspects of the invention herein may have a length of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26 residues.

In one embodiment of the second and third aspects of the invention, the immunogen for forming an immune response according to a method of the invention is a peptide having a sequence of a P2X₇ receptor that may or may not have Pro210 in cis conformation.

The immunogen may be in the form of a P2X₇ extracellular domain or any one or more of the P2X₇ isoforms. The immunogen may be provided for administration in a soluble form or associated with a solid phase such as a cell membrane, bead, or other surface.

Methods for screening peptides that can be used as an immunogen to form an immune response according to the methods of the invention herein are disclosed herein. One example includes the use of erythrocytes in a rosetting assay. In this assay an antibody that binds to functional receptors is used as a positive control in which rossettes are observed. A test antibody is determined not to bind to functional receptors if it fails to form rossettes. It is determined to bind to non-functional receptors if it is observed to bind to a non-functional receptor-expressing cell line, including those discussed herein.

The peptides of the invention can be made by any number of techniques known in the art including solid phase synthesis and recombinant DNA technology.

As is known in the art, a Carrier is a substance that may be conjugated to a peptide epitope thereby enhancing immunogenicity. Some carriers do this by binding to multiple peptides so as to provide an antigen of increased molecular weight to the host in which the immune response is to be developed.

Preferred carriers include bacterial toxins or toxoids. Other suitable carriers include the N. meningitides outer membrane protein, albumin such as bovine serum albumin, synthetic peptides, heat shock proteins, KLH, Pertussis proteins, protein D from H. influenza and toxin A, B or C from C. difficile.

When the carrier is a bacterial toxin or toxoid, diphtheria or tetanus toxoids are preferred.

Preferably the carrier contains functional groups that can react with the peptide of the invention, or may be modified to be capable of reacting with the peptide.

The immunogen may be administered subcutaneously, intradermally and/or intramuscularly.

In a preferred form, the composition for forming an immune response to a P2X₇ receptor for use in the methods of the invention described herein includes an adjuvant or compound for potentiating an immune response.

A large number of adjuvants are known; See also Allison (1998, Dev. Biol. Stand., 92:3-11; incorporated herein by reference), Unkeless et al. (1998, Annu. Rev. Immunol., 6:251-281), and Phillips et al. (1992, Vaccine, 10:151-158). Exemplary adjuvants that can be utilized in accordance with the invention include, but are not limited to, cytokines, aluminium salts (e.g., aluminium hydroxide, aluminium phosphate, etc.; Baylor et al., Vaccine, 20:S18, 2002), gel-type adjuvants (e.g., calcium phosphate, etc.); microbial adjuvants (e.g., immunomodulatory DNA sequences that include CpG motifs; endotoxins such as monophosphoryl lipid A (Ribi et al., 1986, Immunology and Immunopharmacology of bacterial endotoxins, Plenum Publ. Corp., NY, p 407, 1986); exotoxins such as cholera toxin, E. coli heat labile toxin, and pertussis toxin; muramyl dipeptide, etc.); oil-emulsion and emulsifier-based adjuvants (e.g., Freund's Adjuvant, MF59 [Novartis], SAF, etc.); particulate adjuvants (e.g., liposomes, biodegradable microspheres, etc.); synthetic adjuvants (e.g., nonionic block copolymers, muramyl peptide analogues, polyphosphazene, synthetic polynucleotides, etc.); and/or combinations thereof. Other exemplary adjuvants include some polymers (e.g., polyphosphazenes; described in U.S. Pat. No. 5,500,161), Q57, saponins (e.g., QS21, Ghochikyan et al., Vaccine, 24:2275, 2006), squalene, tetrachlorodecaoxide, CPG 7909 (Cooper et al., Vaccine, 22:3136, 2004), poly[di(carboxylatophenoxy)phosphazene] (PCCP; Payne et al., Vaccine, 16:92, 1998), interferon-γ (Cao et al., Vaccine, 10:238, 1992), block copolymer P1205 (CRL1005; Katz et al., Vaccine, 18:2177, 2000), interleukin-2 (IL-2; Mbwuike et al., Vaccine, 8:347, 1990), polymethyl methacrylate (PMMA; Kreuter et al., J. Pharm. ScL, 70:367, 1981), etc.

In one embodiment of the second and third aspects of the invention, a peptide immunogen containing a sequence of a P2X₇ receptor is provided on the surface of a bacteriophage for immunisation of an animal according to a method of the invention described herein.

In still further aspects, the invention provides a kit or composition for use in the treatment of a cancer in a companion animal, the kit including:

-   -   a whole antibody, or a fragment thereof including a variable         domain; or     -   a P2X₇ receptor, or a fragment of a P2X₇ receptor;     -   written instructions for use in a method described herein.

Preferably the antibody or fragment binds to a P2X₇ receptor, preferably a non functional P2X₇ receptor. More preferably, the antibody or fragment does not bind to functional P2X₇ receptor.

Preferably the written instructions are in the form of a label or package insert with instructions for use in a method described herein.

EXAMPLES Example 1 Cat 1 (GB)

-   -   Extensive SCCs scalp and lips, area up to 4 cm² and full         thickness of lip. SCC left lip had spread to angle of jaw under         the fur prior to treatment. IHC on SCC left lip stained for         nf-P2X₇ target receptor prior to treatment.     -   Partial efficacy with intratumoral (i.t.) injections     -   Target receptors widespread in affected tissue as revealed by         IHC     -   Single infusion of cancer-specific therapeutic antibody         targeting nf-P2X₇ receptors administered at fluid maintenance         rate at dose of 3 mg/kg     -   Clear signs of tumour clearance by Day 4     -   By Day 14, majority of SCC left lip tumour eliminated, 2 weeks         post treatment, after single dose IV at 3 mg/kg. SCC clusters         above left eye also clearing at 2 weeks post treatment, IV at 3         mg/kg. Fur regrowth over original lesion site now evident     -   Scalp SCCs and lip SCCs largely removed within 5 weeks after 3         IV doses although there are signs of new epithelial tissue being         scratched by the patient. The central SCC lesion in midline of         lower jaw that penetrated into the bone now has the appearance         of white nodular scar tissue. The patient is untroubled by         having the lesion site handled unlike the condition at the         outset of treatment in which severe pain was evident.     -   After 6 monthly IV treatments the condition has resolved with         even new bone growth revealed via X-ray in the inner mandible     -   Total accumulated dose to effect clinical clearances estimated         to be 30-40 mg/kg due to loss of efficacy through appearance of         anti-sheep antibodies over time

Example 2 Cat 2 (AL)

-   -   SCC on nose prior to i.t. injection     -   Only 1× i.t. injection due to general anaesthetic causing         cortical blindness lasting several hours as cat is 21 years of         age     -   Followed up with topical anti-nf-P2X₇ IgG     -   5 days—SCC nose forming new tissue     -   19 days—SCC nose formed more new tissue

Example 3 Cat 3 (PC)

-   -   Pancreatic cancer with metastases to liver and mesentery     -   Mesenteric metastases of order 1 cm not evident by ultrasound         scan after 2 weekly i.v. infusions     -   Evidence of some tumour lysis (liquid) by ultrasound scan after         2 weekly i.v. infusions     -   After 4 weeks the liver secondary had shrunk from 5 to 2 cm         diameter     -   After 4 weeks the 5-6 cm diameter pancreatic primary had         approximately 80% of its mass liquefied     -   Euthanized after end of week 5 due to pancreatic tumour         lysis/haemorrhaging into abdomen and at request of the owner

Example 4 Cat 4 (FH)

-   -   SCC of nose extending from left nostril 2 cm to bridge of nose     -   Biopsy revealed extensive recurrent SCC following treatment by         surgery late 2008     -   After single i.v. dose at 5 mg/kg tumour reduced in size on         upper nasal surface with spongy consistency becoming firm     -   After second weekly infusion the lesion was no longer evident. A         third infusion was applied and at the end of 2 weeks all         clinical signs of the lesion were absent. A further infusion was         applied to ensure elimination of residual preneoplastic cells         that may have been present.     -   Clinically cleared at 21 days with an aggregate dose of 18 mg/kg     -   No recurrence after 14 months so patient appears completely         cured

Example 5 Cat 5 (CO)

History

Patient had a Bowen's-like lesion removed from left temporal region in 2008. It was noted in an examination in March 2009 that this lesion had reappeared and a new lesion had appeared on the opposite side. These were biopsied with the following results:

Diagnosis

Multicentric squamous cell carcinoma-in-situ with moderate to severe serocellular crusting, superficial dermal scarring and moderate perivascular eosinophilic dermatitis. Skin biopsies from left ear.

Moderate hyperplastic perivascular and interstitial eosinophilic dermatitis with moderate superficial dermal laminar fibroplasias. Biopsies from neck.

Multicentric squamous cell carcinoma in situ with moderate hyperpigmentation, moderate serocellular crusting and extensive dermal scarring in more cranial section. Biopsies from right ear.

Comments

The cat has multiple foci of neoplastic transformation of the epidermal and follicular tissue, consistent with a multicentric squamous cell carcinoma in situ or Bowen's-like disease. These lesions are similar to biopsies submitted in June 2008. There is no evidence of invasive squamous carcinoma in the sections examined.

-   -   SCC in situ (Bowen's)     -   No adverse reaction to 5 mg/kg infusion of sheep anti-nf-P2X₇         IgG     -   After 2 weeks the lesions had diminished noticeably but remained         extensive so a second infusion was administered as a result of         the initial improvement     -   All extensive Bowen's lesions cleared following investigation by         veterinary dermatologist who noted a deep SCC in the right ear         canal was only apparent following the clearing of the         superficial lesions and the associated infections. The patient         had to be prevented from lacerating the new epithelium through         scratching by attaching a restriction collar to allow the skin         surface to heal.

Example 6 Dog 1 (CJ)

-   -   History of haemangiosarcoma on ventral abdomen in 30 kg dog.         After multiple surgeries no longer surgical candidate as tumours         so aggressive. Treated with intra-tumoral injection of nfP2X₇         IgG cut and 3 IV infusions of nfP2X₇ affinity purified antibody.         IT injections of 6 mg antibody into cutaneous lesions 6 cm         diameter showed 80% reductions in a week with tumour lysis         evident as distinct serous discharge.     -   Treated for 4 weeks with i.t ×1 and i.v. ×3 doses at 2-3.4 mg/kg     -   Reduction of tumour size following treatment with sheep         anti-nf-P2X₇ IgG     -   Euthanased on Mar. 21, 2010 due to tumour lysis/leakage syndrome         of these large tumours (total mass 1-2 kg) and following owner's         request

Example 7 Dog 2 (MO)

-   -   Transitional cell carcinoma (TCC) with malignant ascites found         to be metastatic mesothelioma at post mortem pathology     -   Treated for 2 weeks with i.v. ×3 doses at 1-2.7 mg/kg with         chemotherapy     -   Tumour reduced by 15% at week 2, although ascites remained     -   Treatment withdrawn on week 3 at owner's request and against         advice of vet

Example 8 Dog 3 (PI)

-   -   Mast Cell Lymphoma between middle two toes front right paw         Start—appearance is hard and projects below foot pad causing         discomfort. Surgery would require removal of front leg to         maintain 3 cm margins     -   Mast Cell Lymphoma Start—1 week post IV 5 mg/kg—volume reduced         40%     -   Mast Cell Lymphoma Start—2 weeks lesion now soft and greatly         reduced in size with no projection below foot pad and no         discomfort evident in dog. Solid core of lesion now confined to         single toe with surrounding reactive cell sac fully pliable.     -   Metastatic lesion in subscapular lymph node undetectable by Week         2     -   Primary lesion remained largely unchanged in appearance for 3         months     -   Dog euthanized at owner's request as primary lesion became         ulcerated under the paw     -   Post mortem biopsies showed patient to free of all tumours, the         primary lesion site was devoid of mast cells, containing         reactive lymphocytes     -   Lesions may have been cleared with aggregate dose of less than         30 mg/kg

Example 9 Dog 4 (BE)

-   -   Osteosarcoma upper left humerus diagnosed via CT scans after         patient presented in extreme pain and lame, ready to be         euthanized.     -   Weekly infusions at 10/mg/kg initiated. Within a week the         patient re-engaged with owners and appeared largely pain free         and wanting to go for walks.     -   CT scan and post treatment diagnostic tissue to be obtained         under general anaesthetic at 9 weeks, thought to be the minimum         time needed for bone regrowth to be readily detectable     -   No sign of tumour cells in biopsy at Week 9 with patient         appearing very well     -   Patient euthanized at 5 months as a result of the left proximal         humerus fracturing. Biopsy of the lesion site showed no evidence         of residual osteosarcoma. A total remission seemed in evidence         but the bone was left thin and brittle by the tumour.     -   In such cases an external splint should be applied to protect         the bone while associated treatment to aid bone regrowth is         undertaken.

Example 10 Dog 5 (WC)

-   -   Metastatic mast cell lymphoma (Grade 2) with high mitotic index         (25). Multiple lesions >5 cm on ribs, shoulder and hind legs.         Placed immediately on weekly IV infusions of 10 mg/kg.     -   Total lesion volume reduced by 75% at end of first week in line         with expectation of rapid clearance as shown by PI.     -   Principal lesion still palpatable but further reduced at the end         of week 2 following a second infusion     -   Extensive analysis of lesion sites by ultrasound and cytology         due at the end of three weeks following three infusions and a         week to elicit a response     -   Final needle aspirates of all lesion sites performed at 3 months         and at 6 months. No evidence of any mast cells.     -   At 13 months patient is considered tumor free.

Example 11 Dog 6 (HL)

-   -   Patient presented with high grade metastatic mast cell tumor         originating on leg with popliteal lymph node involvement.     -   Treatment by infusion at 10 mg/kg weekly for 6 weeks.     -   All swelling abolished by Week 3     -   Pathology at Week 6 showed no mast cells in tumor sites     -   Patient has had no recurrence in a year

Example 12 Antibody Manufacture

Sheep anti-P2X₇ antibodies 500 ug of conjugate (approximately 100 ug of P2X₇, epitope) was diluted in phosphate-buffered saline (PBS) to 0.8 mL and was emulsified with 1.2 mL of Freund's Complete adjuvant. Sheep were injected at multiple, sites both subcutaneously and intramuscularly with the antigen/adjuvant emulsion. Eight weeks later the sheep were again injected with the same amount of conjugate emulsified with Freund's Incomplete adjuvant at multiple sites. This was repeated 4 weeks later and the animals were bled from the jugular vein. The serum collected was tested for antibody specificity. The sheep were then routinely injected and bled at eight week intervals to provide a pool of serum containing the specific antibodies.

Other sheep were injected with the same dose of conjugated antigen similar to the schedule above but a different adjuvant was used. In these animals, 0.7 mL of the diluted antigen was mixed with 0.1 mL of a Quill A/DEAE Dextran solution (2.5 mg Quill A+25 mg DEAE Dextran per mL of PBS) and 1.2 mL of ISA 50V Montanide. The emulsion was injected at multiple sites both subcutaneously and intramuscularly. The antibodies produced using this adjuvant produced the same specificities as those produced using Freund's adjuvant.

Antibodies were raised in rabbits using the same two adjuvants as with the sheep and the same injection schedules, the only difference being that 300 ug amounts of the conjugate were used for the injection. The antibodies raised had the same specificities as those produced in the sheep and could readily discriminate between the epitopes against which they were raised.

Antibodies were raised in mice against the conjugated epitopes and also against the unconjugated epitope of the non-functional P2X₇ epitope (which is able to discriminate receptors that cannot from pores and thus fail to be apoptotic). In these experiments, the adjuvant used was the QIAGEN Pty Ltd product, ImmunEasy which contains the immuno-stimulatory product CpG DNA (trademark of Coley Pharmaceutical Group Inc.). 62.5 ug of epitope or conjugated epitope/mouse was diluted in 60 uL of PBS and 25 uL of ImmunEasy adjuvant. Mice were injected at multiple sites subcutaneously and intramuscularly. This regime was repeated two weeks later and again at a further two weeks. Mice were bled eight days after the third injection. Antibodies raised in mice by this method were again able to discriminate between the different P2X, epitopes and the antibodies against the P2X₇ non-functional epitope gave the same results as those raised in sheep and rabbits.

Example 13 Induction of Immune Response in Companion Animals

Material and Methods

Peptide

Peptide immunogen was synthesised to high purity in the form GHNYTTRNILPGLNITC (SEQ ID NO: 3) to which was added the cross-linker maleimidocaproyl-N-hydroxysuccinimide (MCS) at the C-terminal Cys residue. The peptide was cross-linked to a carrier protein Keyhole Limpet Hemocyanin (KLH) such that the average percentage of peptide to total peptide-protein conjugate was 40%. This peptide or the alternative peptide GHNYTTRNILPGAGAKYYKENNVEKC (SEQ ID NO:33) similarly conjugated to KLH constituted selective epitope targets, primary and compound respectively that enabled differentiation of the nfP2X₇ receptors to be made from native receptors.

Adjuvant

Imject Alum, an approved adjuvant commonly used in human immunisations, consisting of an aqueous formulation of aluminium hydroxide and magnesium hydroxide plus inactive stabilisers in a gel, was used. The peptide-protein conjugate was added at a concentration of 2.5 mg/mL conjugate (1 mg/mL peptide) dropwise with thorough mixing in the adjuvant in an amount equal to 0.5 mL conjugate to 0.75 mL adjuvant containing 0.5 mg of target peptide epitope.

Immunisation

The immunisation schedule consisted of a primary inoculation (two injections subcutaneously and two injections intramuscularly) of a total of 0.5 mg peptide followed a month later with a boost applied the same way with 0.3 mg peptide. Serum samples were collected immediately prior to and a week post injections. Inoculation is ideally administered no less than a month after the final infusion of anti-nfP2X₇ antibody to ensure no sequestration of the immunogen by residual specific anti-nfP2X₇ antibody infusate.

ELISA

Specific anti-nfP2X₇ antibody responses were measured by ELISA. In brief, the ELISA plate was coated with specific target peptide epitope over which patient serum, is added in a descending concentration. After washing an appropriate secondary anti-human antibody (anti-IgM or anti-IgG types) is applied to detect and determine the concentration of specific human anti-nfP2X₇ antibody present in the patient serum in the form of IgM or IgG.

Following the inoculation, no IgG is detectable but a small amount of IgM is detected. Following the boost, the IgM concentration has returned to a baseline of zero while IgG is produced at higher concentration than the original IgM provided no nfP2X₇ receptor sink is present on extant tumor. In the absence of such a sink in animal patients for which the original tumor has been cleared by anti-nfP2X₇ immunotherapy, a clear population of specific endogenous anti-nfP2X₇ antibody is detected in the serum, of order 25 mg/kg.

FIG. 3 shows the ELISA results for a canine patient, immunized as described above. The levels of free specific circulating antibody are consistent with initial complete clearance and lack of recurrence of metastatic mast cell tumor.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. 

The invention claimed is:
 1. A method for minimising the progression of cancer in a companion animal, wherein the companion animal is a dog, the method including the step of: administering to a dog in which the progression of cancer is to be minimized, a whole antibody or a fragment thereof including a variable domain that binds to a non-functional P2X₇ receptor that is expressed by the dog; thereby minimising the progression of cancer in the dog.
 2. The method of claim 1 wherein the method is for treating cancer or condition or symptom associated with cancer in the dog.
 3. The method of claim 1 wherein the whole antibody or fragment thereof does not bind to functional P2X₇ receptors.
 4. The method of claim 1 wherein the whole antibody or fragment thereof is obtained from polyclonal antiserum.
 5. The method of claim 1 wherein the whole antibody or fragment thereof is raised against an antigen that is xenogeneic to the immune system in which it is raised.
 6. The method of claim 5 wherein the antigen is xenogeneic to the dog.
 7. The method of claim 1 wherein the whole antibody or fragment thereof is xenogeneic to the dog.
 8. The method of claim 1 wherein the cancer is one of hemangiosarcoma, metastatic mesothelioma, osteosarcoma, lymphoma, mast cell tumour, squamous cell carcinoma, mammary carcinoma, melanoma, fibrosarcoma or soft tissue sarcoma. 